Question: What do the following two equations represent? $4x+5y = 2$ $-25x+20y = 1$
Explanation: Putting the first equation in $y = mx + b$ form gives: $4x+5y = 2$ $5y = -4x+2$ $y = -\dfrac{4}{5}x + \dfrac{2}{5}$ Putting the second equation in $y = mx + b$ form gives: $-25x+20y = 1$ $20y = 25x+1$ $y = \dfrac{5}{4}x + \dfrac{1}{20}$ The slopes are negative inverses of each other, so the lines are perpendicular.